Occlusion of the internal carotid artery after radiation therapy for the chiasmal lesion

Incidence, mortality, and cardiovascular diseases in pituitary adenoma in Korea: a nationwide population-based study

PURPOSE

Few nationally representative studies have evaluated the epidemiology of PA (pituitary adenoma). This South Korean study evaluated the incidence of different PA subtypes, cardiovascular disease (CVD), and related mortality.

METHODS

This population-based study evaluated 31,898 patients with PA during 2005-2015. The incidence of PA, mortality, and CVD occurrence in PA cases were evaluated during a median follow-up of 5.3 years (range: 0-10 years). Cox regression analysis was used to evaluate the associations between CVD and mortality.

RESULTS

The annual incidences (per 100,000 population) were 3.5 for non-functioning pituitary adenoma (NFPA), 1.6 for prolactinoma (PRL), 0.5 for growth hormone-secreting pituitary adenoma (GH), and 0.2 for adrenocorticotropic or thyroid-stimulating hormone-secreting pituitary adenoma (ACTH + TSH). The standardized mortality ratios were 1.9 for ACTH + TSH, 1.7 for NFPA with hypopituitarism, 1.4 for NFPA without hypopituitarism, 1.3 for GH, and 1.1 for PRL. During 2005-2015, the overall incidence of CVD among PA patients was 6.6% (2106 cases), and the standardized incidence ratios were 4.1 for hemorrhagic stroke, 3.0 for ischemic stroke, and 1.7 for acute myocardial infarction. The standardized incidence ratios for stroke were significantly higher in the ACTH + TSH and NFPA groups, which also had higher risks of CVD-related mortality, relative to the PRL and GH groups.

CONCLUSION

South Korea had a relatively high incidence of NFPA. The incidence of stroke was highest for ACTH + TSH and NFPA, which was directly related to mortality during long-term follow-up. Patients with these types of PA should receive stroke prevention measures to reduce their risk of mortality.

Systematic review of the incidence and risk factors for cerebral vasculopathy and stroke after cranial proton and photon radiation for childhood brain tumors

Background

The aim of our study is to determine the incidence, timing, and risk factors for cerebral vasculopathy after cranial proton and photon radiation for pediatric brain tumors.

Methods

We performed a single-institution retrospective review of a cohort of children treated with proton radiation for brain tumors. MRA and/or MRI were reviewed for evidence of cerebral vascular stenosis and infarcts. Twenty-one similar studies (17 photon, 4 proton) were identified by systematic literature review.

Results

For 81 patients with median follow-up of 3 years, the rates of overall and severe vasculopathy were 9.9% and 6.2% respectively, occurring a median of 2 years post radiation. Dose to optic chiasm greater than 45 Gy and suprasellar location were significant risk factors. Results were consistent with 4 prior proton studies (752 patients) that reported incidence of 5% to 6.7%, 1.5 to 3 years post radiation. With significantly longer follow-up (3.7-19 years), 9 studies (1108 patients) with traditional photon radiation reported a higher rate (6.3%-20%) and longer time to vasculopathy (2-28 years). Significant risk factors were neurofibromatosis type 1 (NF-1; rate 7.6%-60%) and suprasellar tumors (9%-20%). In 10 studies with photon radiation (1708 patients), the stroke rate was 2% to 18.8% (2.3-24 years post radiation).

Conclusions

Childhood brain tumor survivors need screening for vasculopathy after cranial radiation, especially with higher dose to optic chiasm, NF-1, and suprasellar tumors. Prospective studies are needed to identify risk groups, and ideal modality and timing, for screening of this toxicity.

Delayed cerebral vasculopathy following cranial radiation therapy for pediatric tumors

BACKGROUND

Radiation-induced cerebrovascular injury is a well-known phenomenon. We analyze reported cases of delayed radiation-induced cerebrovasculopathy that present as moyamoya syndrome and/or intracerebral hemorrhage and to statistically analyze the relationship between radiation dose and the interval period between radiation and the presentation of cerebrovasculopathy.

METHODS

Patients ages <21 years at the time of radiation were included in analysis. A review of previous publications yielded 77 cases of delayed radiation-induced cerebrovasculopathy consisting of 45 cases of moyamoya syndrome, 30 cases of intracerebral hemorrhage, and two cases of both.

RESULTS

The median age at radiation was 4.8 years, with a range of 0.5-20 years. Approximately, 75% of these patients received radiation at the age of <9 years. The median interval period for moyamoya cases was 3.3 years (range: 0.3-20; P < 0.001), whereas the median interval period from radiation to presentation for intracerebral hemorrhage cases was 7.5 years (range: 0.8-27). There was significant association between radiation dose and interval from radiation to moyamoya syndrome (P < 0.001), whereas for patients with intracerebral hemorrhage, the association was insignificant (P = 0.31).

CONCLUSIONS

Pediatric patients who presented with moyamoya generally presented earlier than those who presented with intracerebral hemorrhage, suggesting that moyamoya may be a factor that predisposes the patient to intracerebral hemorrhage. In patients who presented with moyamoya, there was a statistically significant correlation between increasing doses of radiation and shorter time from radiation to disease presentation.

Moyamoya syndrome after radiation therapy: case reports

Potentially harmful effects of irradiation on the developing central nervous system have been well documented. We report 2 pediatric patients with moyamoya syndrome developed after irradiation.

CASE

A 3-year-old girl had received 4,860 cGy of postoperative radiation for optic pathway glioma. Cerebral angiography 7 months after completion of the radiation therapy revealed progressive cerebral arterial occlusive disease, involving the internal carotid artery on either side of the circle of Willis, with abnormal netlike vessels. Another 5-year-old girl had received 3,600 cGy of postoperative radiation on the cerebrum for a medulloblastoma. Two years later, she was diagnosed with moyamoya syndrome and treated with indirect revascularization. She died due to further progressive obstruction of the right M1 and A1 on the unoperated hemisphere, in spite of well-developed collateral circulation from the superficial temporal artery and middle meningeal artery on the operated left hemisphere. We suggest that radiation therapy with portals typically including carotid siphon may particularly cause vascular damage, regardless of the tumor pathology and lead to radiation-induced moyamoya syndrome. The prognosis may be poorer in case of poor collateral flow and rapid progression. The radiation therapy may cause fatal vascular damage so it should be taken into consideration when a treatment plan is being formulated for young patients.

Radiation-induced moyamoya syndrome

PURPOSE

The moyamoya syndrome is an uncommon late complication after radiotherapy (RT).

METHODS AND MATERIALS

A PubMed search of English-language articles, with radiation, radiotherapy, and moyamoya syndrome used as search key words, yielded 33 articles from 1967 to 2002.

RESULTS

The series included 54 patients with a median age at initial RT of 3.8 years (range, 0.4 to 47). Age at RT was less than 5 years in 56.3%, 5 to 10 years in 22.9%, 11 to 20 years in 8.3%, 21 to 30 years in 6.3%, 31 to 40 years in 2.1%, and 41 to 50 years in 4.2%. Fourteen of 54 patients (25.9%) were diagnosed with neurofibromatosis type 1 (NF-1). The most common tumor treated with RT was low-grade glioma in 37 tumors (68.5%) of which 29 were optic-pathway glioma. The average RT dose was 46.5 Gy (range, 22-120 Gy). For NF-1-positive patients, the average RT dose was 46.5 Gy, and for NF-1-negative patients, it was 58.1 Gy. The median latent period for development of moyamoya syndrome was 40 months after RT (range, 4-240). Radiation-induced moyamoya syndrome occurred in 27.7% of patients by 2 years, 53.2% of patients by 4 years, 74.5% of patients by 6 years, and 95.7% of patients by 12 years after RT.

CONCLUSIONS

Patients who received RT to the parasellar region at a young age (<5 years) are the most susceptible to moyamoya syndrome. The incidence for moyamoya syndrome continues to increase with time, with half of cases occurring within 4 years of RT and 95% of cases occurring within 12 years. Patients with NF-1 have a lower radiation-dose threshold for development of moyamoya syndrome.

Vascular complications of cranial radiation

OBJECTIVES

Cerebral vascular disease has been reported as a long-term complication of cranial radiotherapy. The purpose of this study was to examine the frequency and risk factors associated with development of cerebral vascular disease in children after cranial radiation.

MATERIALS AND METHODS

A retrospective chart review of all cancer patients treated between 1985 and 2003 who were under the age of 18 years at the time of initial radiotherapy was performed. Variables examined include diagnosis and site of malignancy, age at the time of radiotherapy, sex, total radiation dosage, number of fractions, duration, and whether the patient had proven cerebral vascular event.

RESULTS

Two hundred and forty-four patients met the study criteria. One hundred and 13 cases involved tumors of the central nervous system. The remaining patients had systemic neoplastic disease. Post radiation cerebral vascular disease occurred in 11 (5%) patients, and all but one patient had a tumor involving the central nervous system (mainly in the posterior fossa and supratentorial midline).

CONCLUSION

There is an increased risk of cerebral vascular disease after radiation therapy in childhood, especially in children who received high dose radiation at the posterior fossa and supratentorial axial region.

Moyamoya-like vasculopathy (moyamoya syndrome) in children

INTRODUCTION

A large variety of inherited or acquired childhood disorders and conditions may present in conjunction with progressive bilateral stenosis and/or occlusion of the terminal segments of the internal carotid artery. In addition, the development of pathological collateral vessels can be observed in the vicinity of the steno-occlusive changes in these patients. This condition is known as moyamoya-like (MML) vasculopathy. The natural history, the angiographic appearance, and the pathology of MML vasculopathy probably differ from those of definite moyamoya disease. Adequate cerebral vascular imaging should be considered in all pediatric patients with inherited or acquired systemic disorders and symptoms attributable to cerebral ischemia.

CASES AND DISCUSSION

We present four pediatric cases of MML vasculopathy, and outline the etiology, the current classification, and the therapeutic approaches for this heterogeneous disease entity.

Growth hormone-secreting pituitary adenoma associated with primary moyamoya disease--case report

A 40-year-old female presented with growth hormone (GH)-secreting pituitary adenoma associated with primary moyamoya disease manifesting as amenorrhea, acromegaly, and transient ischemic attack. Magnetic resonance (MR) imaging revealed a tumor mass extending from the sella turcica to the suprasellar cistern, and MR angiography demonstrated stenoses in the bilateral internal carotid arteries with basal moyamoya vessels. Her blood GH and insulin-like growth factor (IGF-1) levels were elevated to 78.94 and 923.0 ng/ml, respectively. The patient underwent removal of the pituitary adenoma because her ischemic symptoms disappeared after oral aspirin medication. Subtotal resection resulted in persistence of the high blood GH and IGF-1 levels. Postoperative MR angiography showed progression of the stenoses in the bilateral internal carotid arteries. Excess systemic GH and IGF-1 may participate in the progression of vascular disease and so could have caused the deterioration of the moyamoya disease.

Visual loss in childhood

An eight-year-old girl presented with vision loss and optic atrophy. Neuro-imaging revealed a sellar mass, which when biopsied proved to be a chiasmatic/hypothalamic glioma. The differential diagnosis of a sellar mass in childhood is discussed, and the presentation and management of chiasmatic/hypothalamic gliomas is reviewed.

Radiation-induced cerebrovasculopathy of the distal middle cerebral artery and distal posterior cerebral artery--case report

A 15-year-old girl underwent partial removal of a pituitary adenoma followed by local irradiation of the brain with a total of 70 Gy through two lateral opposing ports. Twenty years later, she experienced frequent transient ischemic attacks with left sensory disturbance. Cerebral angiography revealed stenoses of the right distal middle cerebral artery (MCA) and the right distal posterior cerebral artery without net-like vessels. There was a severe decrease of vasoreactivity in the right hemisphere. Right superficial temporal artery (STA)-MCA anastomosis was performed. Her neurological deficits were resolved and perfusion reserve capacity had markedly improved 6 months later. We recommend STA-MCA anastomosis in such cases.

The incidence of cerebrovascular accidents in patients with pituitary adenoma

BACKGROUND AND PURPOSE

Patients with pituitary adenomas are effectively treated with a combination of surgery, radiotherapy, and medical therapy. Nevertheless, long-term studies suggest increased mortality that is independent of tumor control, with cerebrovascular accidents (CVA) as the major contributing cause. The purpose of this study was to define the frequency of CVAs in a cohort of patients with pituitary adenoma and identify potential predisposing factors.

PATIENTS AND METHODS

A cohort of 331 United Kingdom (UK) residents with pituitary adenoma treated at the Royal Marsden Hospital (RMH) between 1962 and 1986 was studied. The frequency of CVA was assessed from RMH and referring hospital records and clinicians, by postal questionnaire of referring hospitals and general practitioners, and by examination of all death certificates. The data were analyzed by actuarial methods, and risk factors were assessed by multivariate analysis. The data were compared to the incidence of CVA in the general population using a published UK population cohort.

RESULTS

Sixty-four of 331 patients developed CVA after primary treatment of pituitary adenoma. The actuarial incidence of CVA was 4% (95% CI: 2-7%) at 5 years, 11% (95% CI: 8-14%) at 10 years, and 21% (95% CI: 16-28%) at 20 years measured from the date of radiotherapy. The relative risk of CVA compared to the general population in the UK was 4.1. Age was an independent predictive factor for CVA. However, the relative risk in comparison to the general population was independent of age. The relative risk of developing CVA was higher in women compared to men, in patients undergoing debulking surgery compared to less radical procedures, and in patients diagnosed and treated in the 1980s compared to previous decades. The dose of radiotherapy was an additional independent prognostic factor on multivariate analysis.

CONCLUSION

Patients with pituitary adenoma treated with surgery and radiotherapy have a significantly increased risk of CVA compared to the general population. The factors which may contribute to the increased risk include the presence of pituitary adenoma and consequent endocrine disturbances and the treatment, particularly the extent of surgery and the dose of radiotherapy. When assessing the value of treatment strategies, it is therefore important to include not only intermediate endpoints of tumor and hormonal control, but also late toxicity, including the incidence of CVA and overall survival as the primary endpoint. The potential predisposing factors for CVA need further elucidation to develop treatment strategies with lower risk and consequently, reduced mortality.

Multiple causes of cerebrovascular events in children with tumors of the parasellar region

Cerebrovascular arterial occlusion is a rare but devastating event causing long-term morbidity in children with tumors in the parasellar region. While usually associated with radiation therapy, there are a variety of host, tumor and treatment factors which predispose patients to significant vasculopathy. Case reports of 5 patients from St. Jude Children's Research Hospital with tumors in the parasellar region who presented with or developed vascular occlusive disease are summarized. Multiple factors are identified in these cases which probably impacted on the development of cerebral arterial occlusion with or without moyamoya syndrome. These include, but are not limited to, neurofibromatosis, tumor encasement of major cerebral vessels, surgical alterations, and radiation therapy. The literature supports multiple, potentially interactive etiologies for the development of vascular events in these patients, suggesting that their development is not simply a phenomenon related to radiation therapy.

Large intracranial vessel occlusive vasculopathy after radiation therapy in children: clinical features and usefulness of magnetic resonance imaging

PURPOSE

To assess the relationship between large intracranial vessel occlusive vasculopathy (vasculopathy) and radiation therapy, and to clarify the clinical efficacy of magnetic resonance (MR) imaging in the diagnosis and screening of the vasculopathy.

METHODS AND MATERIALS

We retrospectively evaluated the medical records and serial MR images for 32 pediatric patients, in whom radiation therapy had been given to fields including the circle of Willis and major cerebral arteries. All children had periodically undergone follow-up neurologic assessment and MR imaging examinations at Kanagawa Children's Medical Center for more than one year after radiation therapy (range 1.3-14 years). Patients who had not remained free of tumor progression up to the time of final evaluation were excluded.

RESULTS

Vasculopathy developed in 6 of 32 patients 2-13 years after radiation therapy. Three of them presented with transient ischemic attacks (TIA) and the other three showed infarctions without preceding TIA. Steno-occlusive changes of major cerebral arteries were identified by MR imaging in all six patients, but not obtained in the remaining 26 patients. In the patients with TIA, MR imaging demonstrated steno-occlusive changes at the time of TIA, before irreversible infarction. They have been doing well subsequent to encephaloduroarteriosynangiosis. In the three patients who presented infarction without preceding TIA, MR imaging did not demonstrate the vascular change before the onset of infarction, and two of them developed neurologic deficits. The mean exposure dose for the circle of Willis and major cerebral arteries in these six patients was significantly higher than that in the remaining 26 patients without this sequela (61 Gy vs. 50 Gy, p < 0.05). The mean age at radiation therapy of the six patients was lower, but the difference was not significant.

CONCLUSION

The incidence of vasculopathy after radiation therapy has a considerable correlation with radiation dose and age at radiation therapy. MR examination is useful for the diagnostic evaluation of vasculopathy, and it is also effective in screening for vasculopathy in patients with TIA, and may be helpful in the prevention of neurologic sequela.

Radiation-induced injury to the carotid artery: a longitudinal study

Therapeutic radiation can lead to damage of arterial walls. In the present investigation, we studied prospectively 16 patients without pre-existing vascular disease (13 males, three females; mean age = 59.75 ± 11.9 years) who had undergone surgery and post-operative radiation therapy (cumulative dose = 56.2 ± 10.2 Gy) for the treatment of carcinoma of the head and neck. The carotid arteries were examined every 3 months for 19.9 ± 8.7 months using Doppler ultrasound and B-mode sonography. The thickness of the arterial walls was determined using an index (outer:inner mean arterial wall), and it was compared to a group of age-matched control subjects (n = 16) with healthy arteries. The index of the common carotid artery (CCA) was initially 1.14 ± 0.04 in both the right and left CCA in the radiation-treated subjects. By the end of the study, this index had increased significantly to 1.37 ˙ 0.14 in both right and left CCA in the radiation-treated subjects (p < 0.01). There was a significant difference in arterial wall thickness between the radiation-treated and control subjects (p < 0.001). Frequent and extensive smooth-surfaced plaques indicative of arterial thickening in the area of the common carotid and internal carotid arteries were seen in the irradiated patients. Four patients developed > 50% atherosclerotic stenosis of the internal carotid artery. These data suggest that arterial damage may occur following radiation treatment of the head and neck area. Modification of radiation therapy for the post-surgical treatment of head tumors coupled with the continuous monitoring of the carotid arteries using B-mode sonography could minimize this arterial damage.

Progressive cerebral occlusive disease after radiation therapy

BACKGROUND

A case of progressive irradiation-induced cerebral vasculopathy with abnormal netlike vessels and transdural anastomoses (moyamoya syndrome) is presented. Radiological findings in an additional 40 cases reported in the literature are analyzed, and their clinical relevance is discussed.

CASE DESCRIPTION

A 19-year-old woman presented with recurrent ischemic brain lesions after radiation therapy for treatment of a craniopharyngioma during childhood. Cerebral angiography 6 and 12 years after completion of radiation therapy revealed progressive cerebral arterial occlusive disease involving the internal carotid artery on either side of the circle of Willis, with abnormal netlike vessels and transdural anastomoses (moyamoya syndrome).

CONCLUSIONS

Extensive similarities between irradiation-induced cerebral vasculopathy and primary moyamoya syndrome (Nishimoto's disease) support the notion that both disorders share common pathophysiological mechanisms. The occurrence of moyamoya-like vascular changes may not depend on specific trigger mechanisms but may rather represent a nonspecific response of the developing vascular system to a number of various noxious events.

Intracranial arterial occlusion associated with high-activity iodine-125 brachytherapy for glioblastoma

We describe two patients who developed devastating strokes due to intracranial arterial occlusion 15 weeks and 97 weeks following high dose stereotactic iodine-125 brachytherapy for glioblastoma multiforme. In both cases the occlusion was within the implant volume at points receiving 110-281 Gy and there was no other evidence of significant atherosclerosis in the patients. We therefore conclude that these complications were a direct result of the brachytherapy. The phenomenon of radiation-induced occlusion of large cerebral arteries is reviewed.

Pituitary tumors and aneurysms: case report and review of the literature

A case of acromegaly from a growth hormone-secreting pituitary adenoma associated with dilatation of all major intracranial arteries and bilateral giant, cavernous aneurysms is presented. Although saccular aneurysms are randomly associated with all types of pituitary tumors, the frequency of this happening with growth hormone-secreting or "chromophobe adenomas" is greater than would be expected by chance alone. Intrasellar saccular aneurysms contiguous with tumors have been reported. Bilateral cavernous carotid aneurysms have also occurred in association with pituitary tumors. Both infectious (bacterial and fungal) and traumatic aneurysms can develop as complications of pituitary surgery. A single case of aneurysms due perhaps to actual tumor infiltration of the arterial wall has been reported. Radiation therapy has rarely been associated with aneurysmal dilatation for nonpituitary tumors and has been reported only once after treatment of a pituitary tumor. Aneurysms may mimic pituitary tumors by producing endocrine disturbances, such as hypopituitarism, hyperprolactinemia, and diabetes insipidus, and by compressing adjacent cranial nerves. Anomalous large arteries, such as the trigeminal or transsellar-carotid variants, may run through the sella, and there is a case reported in which the former was associated with a pituitary tumor. A knowledge of these aneurysmal types and vascular anomalies is essential for the pituitary surgeon. Magnetic resonance imaging is now the radiological procedure of choice in the preoperative assessment of patients suspected of having pituitary tumors or recurrences, because, in addition to depicting the tumor, it defines the arterial anatomy and excludes all but very small coexistent aneurysms.

Optic chiasm glioma associated with inappropriate secretion of antidiuretic hormone, cerebral ischemia, nonobstructive hydrocephalus and chronic ascites following ventriculoperitoneal shunting

An optic chiasm glioma may cause loss of vision, endocrine disturbances, hydrocephalus and cerebral ischemia due to its proximity to the pituitary, hypothalamus, III ventricle and internal carotids. A 3-month-old infant with optic chiasm glioma developed hypopituitarism and inappropriate secretion of antidiuretic hormone with plasma hypo-osmolality. The cerebrospinal fluid (CSF) protein concentration was markedly elevated. The impairment of fluid absorption via arachnoid villi and peritoneum by the high protein content, and reversed osmotic gradient between protein-rich CSF and hypo-osmolar plasma may have contributed to both nonobstructive hydrocephalus and recurrent ascites following ventriculoperitoneal shunting. Cerebral ischemia from carotid compression may have led to cerebral atrophy.

Incidence of cerebral infarction after radiotherapy for pituitary adenoma

The incidence of cerebral infarction was studied in 156 patients irradiated for treatment of pituitary adenomas. Seven patients experienced strokes at intervals of 3.2 to 14.6 years after irradiation. The observed incidence was not significantly greater than the expected value of 3.5 strokes (P = 0.078). Six strokes occurred in patients receiving equivalent doses (ED) of 1070 ret or more (observed to expected ratio 3.87, significantly elevated; P less than 0.001). Univariate log-rank analysis showed that the risk of stroke was significantly higher (P = 0.010) in patients receiving an ED of 1070 ret or more (4180 cGy/22 fractions) than those receiving lower doses. Multivariate analysis, however, demonstrated that the increased risk of stroke was associated only with increasing age (P less than 0.0001), not ED (P = 0.148). Due to these inconsistent statistical results, no definitive conclusions could be reached about the relationship between radiation dose to the pituitary and subsequent cerebral infarction.

Ischaemic stroke in the basal ganglia and internal capsule in childhood

Ischaemic stroke in childhood is rare. In particular, there have only been a few reports of lacunar infarcts in children. In this study, four children with true lacunar infarcts and four with larger subcortical infarcts are described. We compare the clinical features and the possible pathogenesis of ischaemic strokes in the basal ganglia and internal capsule in childhood with those in adults, and discuss diagnostic and therapeutic management.

Gliomas of the optic nerve or chiasm. Outcome by patients' age, tumor site, and treatment

A review of the literature revealed 623 cases of optic gliomas with sufficient information to permit actuarial (life-table) analysis concerning the prognosis of this disease by the patients' age, tumor site, treatment, and presence of concomitant neurofibromatosis or extension into the hypothalamus or ventricle. All of these factors are important. The development of mathematical models led to the conclusion that these tumors, generally regarded histologically as low-grade astrocytomas, actually have a very wide but continuous range of growth rates. Some grow rapidly enough to be explained by simple exponential doubling at a constant rate, but most behave as though their growth decelerates. Decelerating growth rates make comparisons of various groups of patients difficult. No support is found for the classical hypothesis that some may be hamartomas. Inadequately treated gliomas of the optic nerve or chiasm bear about the same poor prognosis. However, tumors of the optic nerve (intracranial as well as intraorbital) have an excellent prognosis following complete surgical excision and only a slightly poorer prognosis following irradiation. About 5% of optic nerve gliomas recur in the chiasm following "complete" intraorbital excision. Patients with neurofibromatosis have about twice the recurrence rate following complete excision of an intraorbital glioma. Optic chiasmal gliomas appear to respond to irradiation with doses above 4500 rads. Patients with neurofibromatosis have about the same prognosis as patients without neurofibromatosis following irradiation of a chiasmal glioma.